Surface maintenance machines, for example hand-held surface scrubbers which typically have a rotatable head attached to an elongated handle, wherein a motor situated in the head causes a series of brushes or a cleaning pad to rotate, suffer handling problems caused by vibrations due to unbalanced paddrives, pads or brushes. These vibration problems are especially disturbing on high speed machines, whereby the brushes and the pads rotate up to 400 rpm, and make such surface maintenance machines very difficult to operate and manage, and have even led in some cases to operator injury. These machines are very difficult to control since they typically operate at a frequency of 6.6 movements per second which is difficult to follow with the hand. Furthermore the scrubbing pads and brushes often become deformed through use which increases the vibrations travelling through the head. These handling problems caused by vibrations when operating surface maintenance machines, have been recognised in the prior art. For instance, U.S. Pat. No. 5,507,061 refers to a rotary brush floor polisher containing shock absorbing members which are indicated to reduce vibrations and noise in operation. The floor polisher disclosed in this document contains an upper disk and a lower disk which are connected to each other by a plurality of bolts arranged around the perimeter of the upper disk which bolts are associated with shock absorbers. However, this rather complicated constuction does not fully eliminate vibrations when operating the floor polisher.
Another type of problems relating to known surface maintenance machines is concerned with the following. On starting up known surface maintenance machines, a high torque has to be produced in order for an effective working status to be achieved whereby a high current is required which often greatly exceeds the limitation set by fuses within the machine and at the source. This has led to the problem of fuses often blowing on starting up such machines. Furthermore during the start up period, especially on rough surfaces, a large "contra-torque", which can be unmanageable, must be exerted by the operator in order to remain in control over the machine. An object of the present invention is to provide a head assembly for a surface maintenance machine which substantially overcomes one or more of these problems.